This invention relates to improved cylinder-mounted cutters for printing presses, more particularly a cutoff mechanism for cutting a traveling web into a number of pieces subsequent to printing on the web.
Mechanisms of the type with which the present invention is concerned comprise a rotary knife that cooperates with an anvil to cut the traveling printed web into a number of individual production pieces. Generally speaking the rotary knife or die cutter is mounted upon a rotating cylinder and cooperates with a second rotating cylinder upon which the anvil is mounted. The cutting edge or edges of the knife and the working surface of the anvil rotate at the same peripheral speed and the cut is made as a cutting edge moves into and out of engagement with the surface of the anvil.
Since the cutting action of the knife against the anvil involves metal against metal, there is a relatively high amount of knife wear, thereby resulting in necessity for frequent knife replacement. Moreover, the setup or "make ready" time for knife replacement is substantial. In this regard the knife or cutting die, as it is sometimes called, is mounted on a base member which, in turn, is mounted on the rotatable cylinder. The attachment of the knife to the base is generally through a multiplicity of bolts which must hold the knife in a precise position for proper engagement with the anvil. Typically it is necessary to mount the knife on to the base and then tighten down on the bolts to provide a coarse adjustment for the position of the knife. The anvil and knife cylinders are then rotated until the knife engages the anvil causing the knife to set itself in the proper position. Thereafter, each of the bolts holding the knife to the base is precisely tightened to a specified torque to hold the knife in its final or adjusted position.